19. Chemical Thermodynamics

Consider the combustion of butane gas and predict the signs of ΔS, ΔH and ∆G.

C₄H₁₀ (g) + 13/2 O₂ (g)  ⟶  4 CO₂ (g) + 5 H₂O (g)

You calculate the value of ΔG for a chemical reaction and get a positive value. Which would be the most accurate way to interpret this result?

What are the signs of ∆H, ∆S and ∆G for the spontaneous conversion of a solid into gas?

Nitrogen gas combines with fluorine gas to form nitrogen trifluoride according to the reaction below at 25^oC:

N₂ (g)  +  3 F₂ (g)  →  2 NF₃ (g)               ΔH^o = -249.0 kJ                       ΔS^o = -278 J/K

Calculate ΔG^o and state if the reaction favors reactants or products at standard conditions.

3 C (s, graphite) + 4 H₂ (g) → C₃H₈ (g)

Reactions in which there is a negative change in free energy (–ΔG) are:

If ∆G is small and positive which of the following statements is true?

The chemical reaction 2 NO₂Br (g) → 2 NO₂ (g) + Br₂ (g) has a K_eq = 4.50 × 10⁵.

Does the reaction increase the entropy of the Universe? Explain.